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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* Copyright (C) 2019, Raspberry Pi (Trading) Limited
*
* histogram.hpp - histogram calculation interface
*/
#pragma once
#include <stdint.h>
#include <vector>
#include <cassert>
// A simple histogram class, for use in particular to find "quantiles" and
// averages between "quantiles".
namespace RPi {
class Histogram
{
public:
template<typename T> Histogram(T *histogram, int num)
{
assert(num);
cumulative_.reserve(num + 1);
cumulative_.push_back(0);
for (int i = 0; i < num; i++)
cumulative_.push_back(cumulative_.back() +
histogram[i]);
}
uint32_t Bins() const { return cumulative_.size() - 1; }
uint64_t Total() const { return cumulative_[cumulative_.size() - 1]; }
// Cumulative frequency up to a (fractional) point in a bin.
uint64_t CumulativeFreq(double bin) const;
// Return the (fractional) bin of the point q (0 <= q <= 1) through the
// histogram. Optionally provide limits to help.
double Quantile(double q, int first = -1, int last = -1) const;
// Return the average histogram bin value between the two quantiles.
double InterQuantileMean(double q_lo, double q_hi) const;
private:
std::vector<uint64_t> cumulative_;
};
} // namespace RPi
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